lhc cryogenics: “from cool-down & hwc to operation with beam” s. claudet, for lhc cryogenics...

LHC Cryogenics:“From cool-down & HWC

to operation with beam”

S. Claudet, for LHC cryogenics

Extended LTC, 3 Mar’08

S. Claudet - 3rd March 2008 LHC Cryo - extended LTC

Content

• How to operate up to 8 sectors together• Recovery after a quench: how much time does it take?

Is expert intervention required? How can this be improved?

• Equipment folder: tests results, handling of non-conformities, performance below specs, machine as commissioned vs. machine as nominal

• Alarms/signals/SW available in CCC• Piquet/Experts availability

3. Resources

2. Availability

1. Technical issues

4. Tools & Resources


Major Technical issues (1/2)• Being implemented before HWC:

– DFB’s: level gauges, anti-condensation, valves and filters– Stand-alone levels: short term solution being applied

(evolution ?)No remaining technical limitations so far

• To be tested during HWC:– Re-connection of line B (pumping) below 50 mbar– Quench lines at odd points in case large number of cells

would quench– Heat loads, to quantify the remaining capacity for beam

induced loads w.r.t previsionsTime slots to be allocated at best globally


Major Technical issues (2/2)• Identified, not yet launched:

– P8 ex-LEP 4.5K refrigerator: subcooler to be replaced– QRL line D temperature: 20K is an average, not yet all-along– UX85: Tolerance to single-events for PLC’s and electronicsMost of necessary hardware available, time slot to be decided

• Identified, but to remain for some time:– Helium inventory: from 20l/m to > 25l/m– Line Y heat-exchanger: if discovered after cool-down (1, 3, ?)– Stand-alone levels: long term solution ?– Robustness of some electronic cards and features ?Direct impact on recovery time, not on performance for the 1st run

+ Time slots for preventive maintenance, or wait and repair strategy ?


Availability: From 7-8 to others

For future sectors, we maintain our objectives with work on recovery timeBut as well we try to give Cryo Start/Maintain earlyer !

7-8 (2007): 85% for LSS (>1st May’07) 66% for ARC (>1st Jun’07)Target 4-5: 90% for LSS 80% for ARC

ELQA

Cryo Maintain ARC: 63% (Since 14Jan08)

Stand-alone levels

DFB’s valves

Cryo Maintain LSS: 70% - 93% (Since 21Jan08 or 01Feb08)

LHC 45: MTBF: 11 days - MTTR: 48 hrs


Recovery Time after Limited Resistive Transitions

• More than 14 cells or full sector: recovery up to 48 hours• In case of fast discharge (even w/o quench): 2 h recovery (heating due to eddy currents).

(Predictions at design stage)

Achieved or achievable

Now: 2 to 3 times slower


Recovering a quench

2. Larger He Qty released (criteria!):

> Pre-cooling required before LHe re-filling

> Perturbation of global process, to be done by expert

Alternative 1. considered less perturbating for HWC, ideas to make it automatic and < 10 h for a dipole > 10 kA

1. Small He Qty released:

> Usual 1.9K cooling valve at max. opening

> Self adapting and global process kept OK


LHC Cryogenics availabilityRough ideas for discussions

Reminder: a cryogenic system takes time (hours) to recover any kind of stop (seconds)

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Individual availability

Global availability [8 sectors]

Target for HWC

Target for LHC

operationconsidering independent

origins


Availability• MTBF:

– Less perturbations due to EL or CV systems– First results of global effort of teams to work togetherTo be further improved for beams to circulate one day!

• MTTR:– Experience so far with cold compressors helped pump-down to

15mbar to be successful at each try!– Conservative approach to prevent spoiling 15mbar conditions

(2hrs more versus 2 days lost!)– Ideas to make it more automatic are being tested– We will never compensate the time delay for Y lines !

• Quench recovery:– A simple and safe solution is being studied for automation


No Tel SdC

P2 - P4 P6 P8 - P18U. Wagner G. Ferlin F. Millet

JP. Lamboy (P2/2-3)S. Junker (P4/3-4)

+ C. Parente (Apprentissage)

L. Herblin (P18/1-2)

A. Eychenne (P2) G. Vincent (P6) E. Lussi (P18)

N. Navion (P4) E. Millet (P8)

Affectations LHC Cryo CRG-OA

LHC Cryo OP

P18 P2 P4 P6 P8

70081 79240 79440 79640 79840

75084 79241 79441 79641 79841

+ M. Soubiran (Analyse fonctionnelle)

Team Leader: S. Claudet

+ Industrial partner teams in local control rooms (≈ 23 personnes ALLS)

+ 2 posts (C) identified, not yet through !


Working periods• CERN staff:

– Normal working hours + overtime when needed– On-call service: 1 Operator (direct) + 1 Engineer (back-up)Now: mostly to guarantee safety and helium inventory– Expert assistance in CCC for specific tests

• Industrial partner:– Normal working hours + overtime when needed– On-call service: 1 Operator (direct) + 1 Operator (direct) – Afternoon shifts (14h-22h): 2 Operators, mostly for LN2 trucks– Saturdays: 2 Operators, for LN2 trucks and interventions

HWC activities already possible up to 22h and Saturdays !Investigations for 1 Operator in CCC (2 shifts) after logistics with LN2 trucks


Resources• Cool-down of 8 sectors:

– Should be OK with structure in place

• HWC of many sectors in parallel:– Already now, up to 22h and Saturdays– Spring’08, two shifts (week) and Saturdays (day)

• First beams:– We do not have CERN staff (alone) for any kind of shift– Various type of shifts possible via our industrial partner, with

CERN experts and local control rooms (day time) in back-up

• After July 2009:– End of present operation contract, with in-sourcing as reference

solution, to be re-evaluated in 2008


Challenge for Spring’08Preparing tools to help having a quick global overview, and identify what needs to be delegated to local tuning teams or consolidated


Summary• Technical issues treated to allow HWC and first LHC beams• Methodology for cryogenic commissioning in place

• Learning curves for transients on the good way, with automation in progress and team experience growing

• Work started to safely improve “Cryo start” statistics and availability

• OP team structure adapted in January 2008 to face parallelism (x8)• Imminent presence in CCC (2 shifts during week)

We can adapt and redeploy resources until July 2009, (incl. 2 x 5x8) Longer term future to be consolidated

lhc cryogenics: “from cool-down & hwc to operation with beam” s. claudet, for lhc cryogenics...

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